Q.white bird of paradise
the leaves are turning yellow and brownish, what could be the cause?
It could be watering, diseases, pests or environmental.
These links will help you pinpoint the issue.
https://www.gardeningknowhow.com/ornamental/flowers/bop/bird-of-paradise-an-exotic-flower-like-none-other.htm
https://www.gardeningknowhow.com/ornamental/flowers/bop/bird-of-paradise-plant-diseases.htm
https://www.gardeningknowhow.com/ornamental/flowers/bop/bird-of-paradise-yellow-leaves.htm
https://www.gardeningknowhow.com/ornamental/flowers/bop/bird-of-paradise-plant-bugs.htm